Field of Invention:
The invention relates to the field of tubular fabric manufacturing. In particular, the invention relates to the bobbins that are used to wind yarn that is used to make the tubular fabric.
Background of Invention:
In the circular weaving loom, the weft yarn is provided in shuttles rotating along with the reed. In general, the weft bobbin is held between two end flanges which grip the inner surface of the tube of the bobbin, thereby preventing the fall of the tape/yarn off the bobbin during laying of weft yarn in fabric.
Further, as the weft yarn is laid in the fabric, the weft bobbin unwinds (rotates) along its axis in the shuttle body. As the laying of weft yarn is carried out at a constant rate (linear m/s), the rotational speed of weft bobbin increases in shuttle as the bobbin diameter decreases. The higher and varying unwinding rotational speed increases and varies the yarn/tape tension leading to significant variation in the fabric width.
With the continuous development in the winding loom technology, there has been a significant increase in circular loom production speed. This has also increased the bobbin rotational speed, ultimately leading to an increase in the wear of the bobbin tube and higher fabric width variation. Further, the bobbins are provided

with end flanges. The purpose of the end flanges is to contain the winding material on the bobbin and not allow it to come off the bobbin during the unwinding process. The shuttle bobbin holders are made of hard material. During the unwinding process, there is relative movement between the bobbin holder and the bobbin inner tubes. In the case of inner tubes made of soft metals, the rubbing between the end flanges and the bobbin inner tubes leads to wear of the bobbin inner tubes. Generally, as the bobbin tubes are made from aluminium, the formation of metallic dust with wear is higher whereby the fabric gets contaminated.
There are possibilities of using non-metallic core like paper tubes or phenolic resin impregnated tubes. However, such attempts have not been commercially successful as paper tubes are not reusable and phenolic resin tubes are costly due to their complex manufacturing process.
There is need to resolve the problem of fabric width variation while providing durable bobbin tubes by avoiding wear due to rubbing in circular looms.
Objects of Invention:
The main objective of present invention is to reduce the fabric width variation particularly at bottom portion of weft bobbin.
Another objective of present invention is to provide durable bobbin tubes of reduced wear.

Further objective of invention is to provide an economical solution to industry.
Brief Description of Figures:
Figure 1 shows the composite bobbin of the invention
Figure 2 shows the end cover of the invention
Figure 3 shows the assembly of the composite bobbin and the end flange
Figure 4 shows the core tube with end cover fitted on to it
Figure 5 shows a longitudinal sectional view of the core tube of Figure 4
Summary Of Invention:
The invention relates to the field of weaving looms for tubular fabric. In particular, the invention relates to the bobbins that are used to wind yarn that is used to make the tubular fabric. The present invention provides durable bobbin tubes of reduced wear, thereby addressing the problem of unacceptably high wear of the metallic tubes that form the core of the bobbins. In order to achieve the objective, the invention discloses a composite rigid tube (IB) for yarn winding comprising a rigid core tube (1A), and an end cover (5) having a ring (6), characterised in that on the inner surface (2) of said rigid core tube (1A) is provided at least one spoke (4), and that said end cover has at least one protrusion (7) protruding axially from said ring (6), wherein said end cover is push fitted onto each end of said rigid core tube (1 A).
List of Parts:

1. Bobbin; 1A - Bobbin rigid core tube; IB - bobbin composite rigid core tube; 1C - inner diameter of the bobbin rigid core tube; ID - outer diameter of the bobbin rigid core tube
2. Inner surface of the bobbin rigid core tube
3. Outer surface of the bobbin rigid core tube
4. Spokes of the rigid core tube
5. End cover
6. Ring; 6A - edge of the ring; 6B - external surface of ring
7. Protrusions of the end cover; 7A - Outer surface of protrusions
8. End flange; 8A - protrusions of the end flange
Detailed Description of Invention:
In general, a weft bobbin tube is made from aluminium or mild steel, with the outer diameter of around 32 to 34 mm and thickness of 1 to 2 mm. During the running of a circular loom it has been observed that there is significant variation/reduction in fabric width which can be of the order of 8 to 10% compared to the required fabric width, particularly during the end stages of the exhaustion of weft bobbin.
The inventor realised that one way to overcome this problem would be to increase the outer diameter of the bobbin core tube (1A) itself on which the yarn is wound. However, in doing so he would need to also ensure that the inner diameter would be suitable (small enough) for mounting the bobbins on the existing spindles. To

achieve structural integrity and to reduce overall weight of the bobbin, a set of spokes (4) are introduced on the inner surface (2) of the bobbin tube.
In its simplest form the bobbin (1) is simply made of a bobbin core tube (1A).
In present invention, a bobbin tube (1A) is provided having an inner surface (2) and an outer surface (3), wherein a set of spokes (4) is provided on the inner surface (2) - at least one spoke is provided. The outer diameter (ID) of the bobbin (1) was increased to around 40 to 45 mm and inside diameter (1C) was kept suitable for holding on the precedent winding device. As per the present invention, the tube had hollow spoke structure to reduce the overall weight of tube (1).
As a further aspect of the invention, and in order to avoid wear of the end part of the tube (1A), end covers (5) made of polymeric wear resistant materials are introduced on the ends of said tube (1A), thereby making a composite bobbin (IB).
As shown in the figure 1, the bobbin core tube (1A) as per present invention has hollow structure with spokes (4) radially distributed, leading to higher stiffness (compared to conventional bobbins) of the bobbin (1) due to which it is possible to increase the external diameter (1A) of the bobbin (1) and thereby to reduce the rotational speed during exhaustion of weft bobbin. This arrangement helps in

reducing the overall tube weight and manufacturing by economical extrusion process.
The present invention attains the required objectives by disclosing a composite bobbin rigid core tube (IB) which has a bobbin core tube (1A) having a hollow cylindrical shape provided with spokes (4) and specially developed end covers (5) provided at the ends of the bobbin core tube (1A). The end covers (5) have a rim (6) and protrusions (7) that snuggly fit in (or interlock) with the spokes (4) of the bobbin (1) tube. The end covers (5) are push fitted at the end of the bobbin core tube (1A).
In a further aspect, the invention discloses a composite bobbin (IB) that is made of a core tube (1A), an end cover (5), optionally with an end flange (8). The core tube of the bobbin tube (1A) has at least one inwardly directed spoke (4) connecting its inner and outer surfaces (2 and 3). The shape of the spokes (4) provided on the inner surface (2) bobbin tube (1) and the protrusions (7) provided on the end cover (5) correspond to each other so that when the end cover (5) is push-fitted on to the bobbin core tube (1A), there's an effective restriction in place against relative movement between the end cover (5) and the bobbin (1). The at least one spoke (4) is provided to connect the inner and outer surfaces (2, 3) of the bobbin (1), said spoke (4) being positioned radially. The positive connection has the function of a mutual interlocking of the composite bobbin (1) tube and end cap (5) which reliably prevents a rotation and axial displacement of the end cap (5)

with respect to the bobbin (1). It is the end cover (5) that now comes in touch with the end flange (8), rather than the bobbin (1) coming in touch with the end flange (8). Thus, the end cover (5), which is made of durable material, protects the bobbin core tube (1 A) from wear by rubbing at its ends against the end flange (8), whereby the bobbin core tube's (1A) length remains constant, which gives an extremely long life of the bobbin core tube (1 A). Thus, only the end covers (5) are replaced when necessary.
In preferred embodiments, the end cover (5) is developed from plastic, preferably wear resistant polymeric material like polyamide blended with fiber reinforcement and/or black carbon, in general. The end cover (5) may also be made using rubber.
In an another preferred embodiments, the end cover (5) is developed from elastomeric material, preferably wear resistant synthetic rubber material blend with fiber reinforced and/or black carbon.
The end cover (5) may have textured surface for easy gripping and removal, preferably, the texture surface is in form of knurling.
The end flange (8) also has axially extending protrusions (8a), which are more like thin metal strips, which gives them ability to behave like springs in transverse direction. The diameter of the outer surface (7A) of the end flange protrusions is slightly greater than the inside diameter of the bobbin tube (1). Therefore, once

the end flange is push fitted onto the ends of the tube (1), the end flange protrusions (8a) press against the inner surface of the tube 1) and remain securely in place. Therefore, the relative movement between the end flange (8) and the tube (1) is further reduced.
The bobbin tube (1) material is chosen from suitable light-weight material alloys like aluminum alloy which would provide adequate light weight, low wear and higher stiffness.
Further, the bobbins made from the composite rigid tube (IB) has a greater outside diameter compared to a conventional bobbin of relatively same weight. In other words, for example, a 45 mm diameter bobbin of the invention has nearly the same weight as a conventional steel tube of 32 mm. The bobbin of greater diameter is advantageous in upstream of operation like a winder, wherein around around 35 to 50% higher linear speed can be realised for same rpm.
Hence, the bobbins made from the composite rigid tube (IB) are able to wind the incoming yarn/tape at lower tension due to comparatively lower rotational speed and subsequently, during weaving/fabric formation, lower rotational speed results in less unwinding tension, resulting in more uniform width tubular fabric.
In one aspect of the invention, the end cover (5) is made from elastomeric material. In a further aspect of the invention, the edge (6A) of the ring (6) of the

end cover (5) is chamfered. In a still further aspect of the invention, the end cover (5) has a textured external surface (6B) on its ring (6) for easy gripping and removal.
In another aspect of the invention, the rigid core tube (1 A) is coloured in order to assist identification of weft bobbin of different lot and better sensing by weft end sensing device on loom. In yet another aspect of the invention, the rigid core tube (1 A) is perforated in order to decrease the weight of the tube.
From the foregoing discussion, it is evident that the invention has a number of embodiments.
In particular, the invention discloses a composite rigid tube (IB) for yarn winding comprising a rigid core tube (1A), and an end cover (5) having a ring (6), characterised in that on the inner surface (2) of said rigid core tube (1A) is provided at least one spoke (4), and that said end cover has at least one protrusion (7) protruding axially from said ring (6), wherein said end cover is push fitted onto each end of said rigid core tube (1 A).
In another embodiment, the invention discloses a composite rigid tube (IB) wherein the tube (IB) has an end flange that is push fitted onto said end cover (5), wherein said end flange (8) has at least one axially extending protrusion (8 A).

In a further embodiment, the invention discloses a composite rigid tube (IB) wherein the said end flange (8) is made from from any metallic or non-metallic material, preferably selected from a polymeric group consisting of plastic, preferably polyamide, material blend with fiber reinforcement and/or black carbon.
In yet another embodiment, the invention discloses a composite rigid tube (IB) as wherein the plastic is fibre reinforced.
In a further embodiment, the protrusions (7) extend over part of the length of said rigid tube (IB), onve the end cover is fitted onto the regid tube (IB).
In a still further embodiment, the edge (6A) of said ring (6) is chamfered.
In another embodiment, the external surface (6B) of said end cover (5) is rough textured.
In yet another embodiment, the rigid tube (IB) is coloured white for improving the weft end sensor senstivity for black yarn.
While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that

modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

We claim:
1. A composite rigid tube (IB) for yarn winding comprising a rigid core tube (1A), and an end cover (5) having a ring (6), characterised in that on the inner surface (2) of said rigid core tube (1 A) is provided at least one spoke (4), and that said end cover has at least one protrusion (7) protruding axially from said ring (6), wherein said end cover is push fitted onto each end of said rigid core tube (1 A).
2. The composite rigid tube (IB) as claimed in claim 1, wherein said tube (IB) has an end flange that is push fitted onto said end cover (5), wherein said end flange (8) has at least one axially extending protrusion (8A).
3. The composite rigid tube (IB) as claimed in claim 2, wherein said end cover (5) is made from from any polymeric material selected from a group consisting of plastic, preferably polyamide material blend with fiber reinforcement and/or black carbon.
4. The composite rigid tube (IB) as claimed in claim 2, wherein said end flange (8) is made from from any polymeric material selected from a group consisting of plastic, preferably polyamide material blend with fiber reinforcement and/or black carbon.
5. The composite rigid tube (IB) as claimed in claim 2, wherein said end cover (5) is made from from any material selected from a group consisting of elastomeric material, preferably wear resistant synthetic rubber material blend with fiber reinforcement and/or black carbon.

6. The composite rigid tube (IB) as claimed in claim 2, wherein said end flange (8) is made from from any metallic material selected from a group consisting of alloy having springy characteristic.
7. The composite rigid tube (IB) as claimed in claims 1 to 5, wherein said protrusions (7) extend over part of the length of sai rigid tube (IB).
8. The composite rigid tube (IB) as claimed in claims 1 to 6, wherein the edge (6A) of said ring (6) is chamfered.
9. The composite rigid tube (IB) as claimed in claims 1 to 7, wherein the external surface (6B) of said end cover (5) is rough textured.
10. The composite rigid tube (IB) as claimed in claims 1 to 8, wherein said rigid tube (IB) is coloured.
11. The composite rigid tube (IB) as claimed in claims 1 to 8, wherein said rigid tube (IB) is white in colour.